Brake actuator



May 7, 1946, R. A. GoEPRlcH BRAKE AcTUAToR Original Filed Deo. 26, 1959 Patented May 7, 1,946 l UNITED STATI-:s Viux'rslv'r. orricl:

BRAKE Ac'rUA'ron Rudolph s. Geepfrien, south Bend, Ina., assignor to Bendix 311,044, now Patent Y Divided and this Serial No. 494,160V

4 Claims.

This invention relates in general to brakes, and in particular to improvements in actuators for fluid operated brakes. The presentapplication is a division of application Serial No. 311,044, filed December 26, 1939, and issued as Patent No. 2,351,952 on June 20, 1944.

An obj ect of the present invention is to provide an improved brake actuator which also acts as an anchor for one or more brake shoes.

A further object of the, presentinvention is to provide a wheel cylinder which is capable oi' exerting an applying force against the brake shoe even though the shoe is at the time anchored on the wheel cylinder.

f uuid actuator in longitudinal section.

Figure 2 is a section taken along the line 2-2 of Figure 1; and

Figure 3 is a.- section taken of Figure 1.

The brake illustrated in Figures 1 to 3 comprises a drum I0, at the open side of which is a support or backing plate I2, and within which are arranged brake shoes I4 and I8 raced with along the line 3-8 suitable brake lining I8. The lower ends of the shoes are notched to iit against opposite sides of a fixed anchor post 28 mounted on the anchor plate I2, a spring 22 being tensionedbetween the shoes I4 and I6 to urge them toward this anchorage. r

For actuating the shoes I4 and I8 there is provided a cylinder 24 connected at a port 28 to a pressure line (not shown) ot a conventional iluid braking system. Within the cylinder 24 are a ,pair of pistons 28, the inside faces oi' which are Aviation Corporation, South Bend, Ind., a corporation of Delaware` i Original application De cember 26, 1939, Serial No. Y No. 2,351,952, June 20, 1944. application July 10, 1943,

(Cl. 18S- 152) a crown gear 48 is provided, adapted to cooperate with serrations 42 of the anchor cap 88. For locking the anchor cap 38 in positiona spring member 44 is provided, which has its ends arranged as a pawl to cooperate with the serrations 42.

'I'he right end of the wheel cylinder 24 may be provided with a construction exactly like that which has just been described, but as an alternative may take a form which will now be d escribed. The right hand piston member 28 is adapted to cooperate with a plunger 46 which is forked at its right end to engage the web of the shoe I6. Cooperating with the plunger 46, is an exteriorly threaded member 48 which is slotted to be engaged by the web of the shoe I8 and which has two inside diameters thus providing a shoulder against which the plunger member 4 6 abuts. For adjusting the position of 2o the threaded member 48, and the plunger memportions 88 which in edect form cams above and` ber 48,Y there is provided a cap Bil threadably'engaged to the member 48, and which anchors against the` right end of the wheel cylinder 24.

For rotating the cap 88 a crown gear 82 similar to crown gear48 is provided. The anchor cap 88 may be held In locked position by the spring 44 which is adapted t0 act as a pawl to engage serrations inthe cap 8l in a manner similar to that with the left anchor cap 88.

'I'he lower end of the web o t shoe I4 is straddled by two parts of a iloating bell crank lever 84, notched as at 88 to form integral connecting be1ow the menor zo between the ends of the webs of the two shoes. The notch 88 permits the lever 84 to oat horizontally along a chord o! the drum, with the shoes, as one shoe orthe other anchors on post 28 when the brake is approvided with sealing cups 88, held in position by a spring 82.

Adapted to cooperate with the left hand piston member 28 is a plunger 84 which is slotted in the mannershown to embrace the web oi' the shoe I4. The slotted plunger 84 also embraces an adjustable anchoring member' I8 which is screwed into an anchoring cap 88 which lits over and anchors against the end of the wheel cylinder 24. For adjusting the position oi' the brake shoe I4 plied; and since thenotch 88 embraces the anchor post 28 the post prevents vertical movement of the lever. The lever 84 cooperates with a, U- section thrust link 88, adapted to straddle the .web of the shoe I4 in the manner shown, and a rpair of bell crank levers 82 pivoted at 84 on the upper end of the web of the shoe I4. As shown. the end of the plunger 34 is in contact with each bell crank lever 82.

In operation, the pistons 28 are forced apart hydraulically to apply the brake. The right hand piston 28V acts through the plunger 48 directly upon the shoe I 8. The left hand piston 28 acts through the plunger 84 on the levers 82 to act c upon the thrust link 88 and the bell crank lever 84. If the drum is turning clockwise shoe I8 is actuated' by the right hand piston 28 and anchors ated by the thrust of the plunger 3d on the lever 62 and anchors on the post 2b, while the shoe i3 is actuated bythe cam lever 54 and anchors on the cap 50.

Continued operation of the brakes causes wear on the linings, and to bring the linings to 'a desired clearance at the drums anchor caps d@ and 50 are rotated by means of the crown gears til and 52. Rotating crown gear il@ effects rotation of anchor cap 38 causing the bridge member 3B to be moved against the web of shoe i4. The residual pressure in wheel cylinder 2d and the load in spring 32 moves plunger 343 and its attendant piston 2b to the left until the plunger 34 engages levers 32. Similarly, the adlustment of shoe I6 is obtained. Rotation of anchor cap 50 by means of crowngear 52 moves threaded member 48 and plunger member d5 to the right. The residual pressure in wheel cylinder 23 and the load in spring 32 moves the attendant piston 28 to the right. Thus, with the shoes adjusted in the manner described a minimum amount of travel of the pistons 28 is required to bring shoes i4 and i8 into engagement with the drinn upon brake actuation.

While two illustrative embodiments of the actuator have been described in detail it 1s not the intention to limit the scope of the invention to the particular embodiments shown nor otherwise than by the appended claims.

I claim:

1. A combined actuator and anchor member for a brake shoe comprising a cylindeina piston reciprocable in the cylinder, a cap on the end of the cylinder serving as an anchor for the shoe, and a piston actuated plunger extending through said cap and axially movable relative to the cap and shoe, the outer end of the plunger overlying the anchoring end of the shoe and being formed to permit outward movement of the plunger relative to the shoe regardless of the position of the shoe.

2. A combined actuator and anchor member for a brake shoe comprising a cylinder, a piston reciprocable in the cylinder, a cap on the end of the cylinder serving as an anchor for the shoe, said cap having a threaded central opening, an adjustor screwed in the opening in said cap and in contact with the end of the shoe, means for preventing rotation of the adjustor in order that the released position of the shoe may be adjusted by rotating the cap, and a plunger extending through said adjuster and axially movable relative to the cap and adjustor, said plunger beine,r actuated by the piston and being operatively associated with the shoe, thereby permitting actuation of the shoe by the piston when the shoe is anchored on the adjustor and cap.

3. A combined actuator and anchor member for a brake shoe comprising a cylinder, a piston reciprocable in the cylinder, a cap on the end of the cylinder serving as an anchor for the shoe, said cap having a threaded central opening, an adjustor screwed in the opening in said cap and in contact with the end of the shoe, means for preventing rotation of the adjustor in order that the released position of the shoe may be adjusted by rotating the cap, and a plunger extending through said adjuster and axially movable relative to the cap and adjuster.

4. A combined actuator and anchor member for a brake shoe comprising a cylinder, a piston reciprocable in the cylinder, an adjustable anchor member on the end of the cylinder which the shoe contacts when it anchors at that end, and a plunger extending through said anchor member and axially movable relative thereto, the outer end of the plunger overlying the anchoring end of the shoe and being formed to permit outward movement o! the plunger relative to the shoe regardless of the position of the shoe.

RUDOLPH A. GOEPFRICH. 

